The present invention relates to silver salt photothermographic imaging materials, and in particular to thermally processable photothermographic materials exhibiting enhanced photographic performance and improved abrasion resistance and transportability.
In the field of graphic arts and medical treatment, there have been concerns in processing of photographic film with respect to effluent produced from wet-processing of image forming materials, and recently, reduction of the processing effluent is strongly demanded in terms of environmental protection and space saving. There has been desired a photothermographic dry imaging material for photographic use, capable of forming distinct black images exhibiting high sharpness, enabling efficient exposure by means of a laser imager or a laser image setter.
Known as such a technique are silver salt photothermographic dry imaging materials forming photographic images through thermal processing, as described in U.S. Pat. Nos. 3,152,904 and 3,487,075, and D. H. Klosterboer, xe2x80x9cThermally Processed Silver Systemsxe2x80x9d in IMAGING PROCESSES and MATERIALS, Neblette""s Eighth Edition, edited by J. M. Sturge, V. Walworth, and A. Shepp (1969) page 279.
Such a photothermographic material generally comprises a support such as a plastic resin support provided thereon with an emulsion layer in combination with other component layer(s) such as an interlayer, a protective layer, a backing layer, an antihalation layer or an antistatic layer. When a photothermographic material is wound up, re-wound or transported in the process of coating, drying or converting, the photothermographic material is often adversely affected by contact of the photothermographic material sheet with various apparatuses or mutual contact of photothermographic material sheets, such as contact of the light-sensitive layer-side surface with the backing layer-side surface. Examples thereof include abrasion marks or marks produced in slippage on the surface of the photothermographic material and deterioration of the photothermographic material, caused when the photothermographic material is transported in a processing apparatus.
In regard thereto, U.S. Pat. No. 6,021,117 discloses the use of an alkylsilane compound having 8 or more carbon atoms. However, it was proved that there were problems in that the use of such a compound adversely affected photographic performance, deteriorating image color and the desired slipping property was not achieved. Further, in response to recent trends of increases of transport speed or processing speed in a processing apparatus, improvements in slipping property are required.
In view of the foregoing problems, it is an object of the present invention to provide a silver salt photothermographic material improved in abrasion mark caused in processing, without adversely affecting photographic performance.
It is another object of the invention to provide a photothermographic material exhibiting enhanced slipping property, without adversely affecting coatability.
The above object of the invention can be accomplished by the following constitution:
1. A photothermographic material comprising a support provided thereon at least one light-sensitive layer containing an organic silver salt, light-sensitive silver halide grains and a reducing agent, wherein the surface of at least one side of the photothermographic material exhibits a coefficient of dynamic friction of 0.1 to 0.4 when being in contact with a stainless steel plate maintained at a temperature of 100xc2x0 C.
Furthermore, preferred embodiments of the invention are as follows:
2. A photothermographic material comprising a support provided thereon at least one light-sensitive layer containing an organic silver salt, light-sensitive silver halide grains and a reducing agent, wherein any one of the layer(s) provided on the support contains solid lubricant particles;
3. The photothermographic material described in 2 above, wherein the solid lubricant particles are comprised of boron nitride;
4. A photothermographic material comprising a support provided thereon at least one light-sensitive layer containing an organic silver salt, light-sensitive silver halide grains and a reducing agent, wherein any one of the layer(s) provided on the support contains solid lubricant particles and a hydroxy group-reactive compound;
5. A photothermographic material comprising a support provided thereon at least one light-sensitive layer containing an organic silver salt, light-sensitive silver halide grains and a reducing agent, wherein any one of the layer(s) provided on the support contains solid lubricant particles and a fluorinated nonionic surfactant;
6. The photothermographic material described in any of 1 through 5, wherein the light-sensitive layer contains at least a dye represented by the following formula (1): 
wherein X is a sulfur or oxygen atom; R1 and R2 are each a univalent substituent group; and m and n are each 0, 1, 2, 3 or 4;
7. The photothermographic material described in any one of 1 through 6, wherein the light-sensitive layer or a light-insensitive layer contains a silver-saving agent.
8. The photothermographic material described in any one of 1 through 6, wherein the light-sensitive layer or a light-insensitive layer contains at least two compounds generating a labile species capable of oxidizing silver or capable of deactivating the reducing agent, thereby preventing reduction of silver ions of the organic silver salt to silver upon exposure to ultraviolet ray or visible light;
9. A black-and-white silver salt photothermographic material comprising at least two light-sensitive layers;
10. An image recording method of a silver salt photothermographic material, wherein when recording an image on the photothermographic dry imaging material described in any of 1 through 6, exposure is conducted using a laser light scanning exposure machine of double beam scanning laser light;
11. An image recording method of a silver salt photothermographic material, wherein when recording an image on the photothermographic dry imaging material described in any of 1 through 6, exposure is conducted using a laser light scanning exposure machine of longitudinal multiple laser scanning light.
12. The photothermographic material described in any one of 1 through 6, wherein the photothermographic material meets the requirement of 190xc2x0  less than hab less than 260xc2x0 , in which hab is a hue angle (as defined in JIS-Z 8729).
13. The photothermographic material described in any one of 1 through 6, wherein the light-sensitive layer is formed by coating a coating solution of the light-sensitive layer containing at least 30% by weight of water.